Can magnetic fields from powerlines, household wiring, appliances and other electrical equipment increase a person’s risk of cancer? That’s the question that Professor Massimo Maffei, from the Department of Science at the University of Turin in Italy, has answered in a paper published recently in the International Journal of Molecular Sciences.
In his research, Maffei reviewed research on magnetic fields, breast cancer, brain tumours and leukemia published between January 2000 and December 2021. ‘Because cancer is one of the significant problems of global health, epidemiologic [population] studies have faced the question of whether occupational and residential exposure to ELF EMF [extremely low frequency electromagnetic fields] might be carcinogenic,’ he wrote.
He found that, while some studies provided stronger evidence than other, there was research linking magnetic fields with all three types of cancer.
Breast cancer is the most common cancer in women aged 65 and older and claims the most lives. Maffei says that ‘the excessive exposure to MFs [magnetic fields] increases the risk of female breast cancer.’ One theory to account for this is that magnetic fields reduce levels of melatonin, a potent free radical scavenger. Another possibility is that exposure ‘correlates with increased proliferative activity of the mammary epithelium’. Maffei says that ‘there is a growing body of evidence that the use of electric bedding devices may increase breast cancer risk.’
Brain tumours are on the rise in many countries and have been linked to living close to high voltage powerlines. One study found an increased rate of brain tumours in children who were exposed to magnetic fields of 3 or 4 milliGauss (mG).
Leukemia, the most common cancer in children, is also linked to magnetic field exposures. ‘Several meta-analyses showed a statistical association between childhood leukemia and a range of exposure 0.1—2.36 µT MF intensity’ [1—23.6mG], the paper says. According to Maffei, ‘Preventive measures and precautionary principles are necessary to warrant the reduction of exposure to children because of their greater sensitivity to ELF EMF’
In his paper, Maffei points out that some magnetic field exposure comes from electrical sources inside the home, for example the fields generated by electric blankets (which may increase the risk of prostate and testicular cancers).
However, generally higher exposures occur in the workplace and the jobs with the highest exposures include ‘electronics workers, cooks and kitchen workers, cashiers, bakery workers, textile machine operators, and residential and industrial sewing machine operators.’ Maffei says that occupational exposure to magnetic fields has been linked to brain tumours, breast cancer in men and women and leukemia. Exposure of men has been linked to ‘tumours of the liver, biliary passages, kidney, and pituitary gland’. Exposure of women has been linked to ‘an increased incidence of astrocytoma I-IV, for cancer of the corpus uteri and multiple myeloma’ and for men and women there is some evidence of increased risks of ‘non-Hodgkin lymphoma, acoustic neuroma, and thyroid cancer.’
According to Maffei, occupational ‘MF exposure limits are more than a thousand times higher than the magnitudes that are associated with the cancer risks that are observed in epidemiological studies, leaving millions of workers exposed to MF in this large gray area where the public health consequences are unclear.’
Not only do studies on humans show a link between exposure and cancer, but so do studies on animals. ‘Exposure to MF was found to be a cancer promoting factor in animal experiments; animal studies are often used in the evaluation of suspected human carcinogens,’ Maffei wrote.
Maffei pointed out that magnetic fields may not just cause cancers directly, but they may contribute to it in other ways. He says that ‘MFs exert their effect on both human and animal (rat and mice, mainly) cells when used at high intensity and for a long time. The common response is the production of ROS [reactive oxygen species], which trigger a cascade of other cellular responses which might be the direct consequence of MF exposure.’
In 2002, the International Agency for Research on Cancer classified magnetic fields above 4 mG as a class 2B (‘possible’) carcinogen based on studies published prior to Maffei’s review.
Maffei, M.E. Magnetic Fields and Cancer: Epidemiology, Cellular Biology, and Theranostics. Int. J. Mol. Sci. 2022, 23, 1339. https://doi.org/10.3390/ijms23031339; https://www.mdpi.com/1422-0067/23/3/1339/htm